i have a problem with my 94 sunbird 2.0L . I bought the car cheap and now i need to safty and etest it. but its not running properly. When its cold it starts right up and idles fine, but after it warms up is sounds like its gonna run out of gas, the exhaust makes a putt putt putt sound and the engine has a rough idle. I tried changing the plugs, and wires, but still have the problem. it wont idle properly, but as soon as i rev it up, its like there isn't even a problem. I have a feeling it might be the coil pack, cylinders 3 and 4 have a strong spark when i pull off the cable, it throws a spark on the block from 3 inches away. but 1 and 2 still fire, but they are weaker, they only throw a spark when i go to put the cable back on the spark plug. What do you guys think?

Any kind of discoloring on the spark plugs?. Black / White / ?. Could have a bad Head gasket, Bad intake exhaust valve.

I would start with cleaning the throttle body and idle air intake valve with Gunk Injector Medic (under $10 from your local parts store) before replacing coil packs.